About the Nature of the course of BN Reactor beyond Design Accidents under postaccident Core Materials Relocation
In the safety analysis of BN reactor accepted division of beyond design accident into four stages: initial, transitional, postaccident material relocation and postaccident heat removal. Formed in transitional stage as a result of the molten cladding relocation and solidification initial steel blockages of channels for a while impede the flow down of liquid fuel and form a solid foundation for the pool. To move the fuel in channels it is required at first a melting of blockages. After reactor shutdown it is possible in the case of insufficient heat to the surrounding fuel assemblies. Under meltthrough of blockage the melt will be flow into the channels between the yet solid parts of the fuel rods at some length, it hardens there and again forms a layer of blockages. As a result, the process of heatgenerating mass moving will be not smooth, and the intermittent nature and will consist of repeating phases: meltthrough of blockages layer, leaking of melt at some length and solidification, the melting of the next layer, etc.